Fabric finishing machine and automatic control for operating same



Apnl 14, 1970 D. L. RADFORD ET AL 3,505,743

FABRIC FINISHING MACHINE AND AUTOMATIC CONTROL FOR OPERATING SAME Filed Aug. 13, 1968 Jig;

United States Patent 3,505,743 FABRIC FHNISHING MACHINE AND AUTOMATIC CONTROL FOR OPERATING SAME David L. Ratiford and Michael G. Mladejovsky, Salt Lake 'City, Utah, assignors to McGraw Edison Company, Elgin, llL, a corporation of Delaware Fiied Aug. 13, 1968, Ser. No. 752,320 Int. Cl. F26!) 19/00 US. C]. 34-45 14 Claims ABSTRACT OF THE DISCLOSURE A finishing machine for fabrics, including means for moistening and for drying the fabric, and control means that sense the moisture level in the fabric and respond upon certain predetermined levels being reached to control the operation of the machine, such as terminating one and automatically starting the other of the moistening and drying means and thereafter further terminating the other of the moistening and drying means.

This invention relates to a fabric finishing machine, and particularly one having moisture sensing apparatus suitable for operating the machine automatically as a function of the moisture level in the fabric being finished, as contrasted to a timed operation of the machine.

Because fabric finishing machines such as are used in commercial laundries and cleaners generally operate on a wide variety of fabrics having different thicknesses and moisture retaining characteristics, it has been found unsuitable to cycle the machine purely on a timed basis. For example, in a garment pressing cycle where the garment initially is steam moistened and thereafter is vacuum, air or heat dried on a timed basis, it is possible to deviate from that time actually required for either or both steps. Moreover, if the first step, moistening for ex ample, is improper and excessive moisture is added to the fabric, the second step of drying must be extended to overcome the error initialy made. The actual cycle time of the machine accordingly can be substantially more than would be required, and the efficiency of measured machine output compared to maximum machine output can be quite low. Another occasion for poor operating efficiency is where several machines are operated sequentially in a common line so that a delay in the cycle time of the first machine slows down the whole line.

A main object of this invention is to provide in a fabric finishing machine having means for adding moisture to and for withdrawing moisture from the fabric a control for operating the moistening and drying means automatically as a function of the moisture level in the fabric.

Another object of this invention is to provide apparatus which senses a relative change of electrical resistance of a fabric as the moisture level of the fabric varies during the cycle of the finishing machine to determine when any particularly sequence in the cycle has been idealy completed, and which thereafter responds to such a sensed change to terminate the cycle.

A more specific object of this invention is to provide such apparatus including spaced probes which are disposed to contact the fabric to be finished and to complete an electric circuit across the fabric, further including means to sense changes of resistance across the probes due to 3,505,743 Patented Apr. 14, 1970 changes of the moisture level in the fabric, and still further including means responsive to the sensing means to cycle the machine in question.

These and other objects of this invention will be more fully understood after reviewing the following specification, the accompanying drawing of which forms a part thereof, wherein:

FIG. 1 shows a typical garment finishing machine disclosing therein a preferred embodiment of the subject invention;

FIG. 2 is a sectional view as seen generaly from line 2-2 in FIG. 1, except showing the same with the press head in the closed or pressing position;

FIG. 3 is an enlarged view of the portion of the apparatus shown in FIGS. 1 and 2; and

FIG. 4 is a schematic of an electric control suitable for operating the subject apparatus in the manner desired.

The drawings show a press 10 of a conventional scissor type Where a pedestal 12 mounts thereon a table 14 and a stationary buck 16 disposed above the table. An arm 18 is pivotally mounted on pin 20 and supports a head 22 which can be moved against the buck 16 and thus accordingly has a surface complementary to that of the buck. Steam and vacuum lines are brought to the press, and the buck 16 has particular Wall structure for defining a steam heating chamber 28 and a discharge chamber 30 which communicates through apertures 32 with the upper buck surface. Conventionally a pad and cover 34 overlies the upper buck surface to cushion hard objects that may be placed thereon such as buttons, zippers or the like. The head 22 also has wall structure which defines a heating chamber 36 and a discharge chamber 38 which communicates through openings 40 with the press face. Typically, the press face is of a hardened metallic surface, such as stainless steel.

Depending on the particular finishing operation and the type garment to be finished, the conditioned garment, moistened either beore being dressed on the unit or after, is dressed on the unit and is dried in the dressed condition to eliminate wrinkles. The subject invention relates specifically to apparatus for automatically terminating the various moistening and/or drying steps mentioned upon specific moisture levels of the garments being reached.

Basically, the control includes two pairs of sensor probes, each pair having a probe element 42 and 43, and 46 and 47 located on the head and buck respectively, which oppose one another and are adapted further to contact the garment when the press is closed. An electric circuit is established across each pair of probes through the garment, and the concept that this part of the circuit has less electrical resistance when the garment is moist as compared to when it is dry is utilized by proper adjustment to sense when desired moisture levels are achieved during the moistening or drying steps of the cycle and responsive thereto to terminate the particular step.

Referring now to the construction of the probes, note that one probe 42 and 46 of each pair is formed integrally of the head and is at a grounded potential since the machine base preferably is grounded to eliminate potential hazard from electric shock. In certain presses where an aluminum head platen is used for uniform temperature distribution, the aluminum is anodized on its surface for increased hardness and durability. The anodized surface,

being an electric insulator, is typically scratched to expose the aluminum and define the probe in the head. In other head platen constructions of steel or the like, the head itself is of sufiicient conductivity and no special fabrication is needed for it to be used as the one probe.

The other probe 43 and 47 of the pairs is preferably disposed in the padded cover for the buck and is exposed through as Opening in the pad 34. This probe is a brass strip which has a pin connection 50 to a wire 51 that can be connected to the circuit to be described later. The brass strip is preferably surrounded at all locations other than opposite the head probe area with an insulating material such as a Mylar tape 52. This insulates the buck probe from contact with the buck itself or with any resilient metallic construction such as springs 54 which are frequently included as part of the buck cover.

The electric probes of each pair are physically located relative to the press head and buck to oppose one another and to contact the garment preferably at a location where the moisture content thereat would be representative of the most difiicult areas of the garment to dry or moisten. For example, in a press for shirts it would be desirable to locate the probes in the area near the collar which, being of multiple thickness, has the most capacity to absorb and retain moisture.

To operate the press, the head and buck typically are heated by application of steam to chamber 28 and/or 36 and the garment is dressed on the buck. In the case of a laundered item, the garment is generally moist already and no additional conditioning is required; whereas with a dry cleaned item, conditioning steam is generally directed against the garment from chamber 30 or 38. Considering the typical dry cleaning press cycle, after the garment is dressed on the buck and the head closed, steam is discharged from the head and/or the buck until the garment is adequately moistened and the sensor probes detect this by the reduction in resistance across the spacer probes. The sensor control then terminates steam discharge and begins the required pressing cycle. This frequently is accompanied by drawing vacuum in the buck or head chambers 30 and 38 and by additive squeezing pressure applied between the buck and head. The sensor probes thereafter senses when sufiicient moisture has been driven off from the garment to terminate the drying cycle. Thereafter the press head is opened to permit the operator to remove the finished garment from the press.

The schematic of control apparatus suitable for operating the press in the manner described above is disclosed in FIG. 4. The control includes 120-vo1t AC. power input lines 60 and 62 with line 62 being grounded to the machine frame. A limit switch 63 in line 62 is mechanically closed upon the head contacting or approaching the buck to start the initial machine cycle, and moreover precludes premature and false activation of the circuit before the head and buck closed. Solenoids 64 and 65 are operable to control the particular steam discharge and/or vacuum drawing control valves in the head and buck, which can be accomplished in any well-known manner. In other words, the solenoid 64, when energized, causes the press to function in the moistening step and physically would open an appropriate steam valve (not shown), or the like; whereas solenoid 65, when energized, causes the press to stop the drying step and physically would control the vacuum drying and additive squeezing force means. In series connection with these solenoids are normally closed switch 68 with solenoid 64 and normally open switch 69 with solenoid 65. The apparatus further includes a moistening control M and a drying control '1), and the switches are actuated by relays 72 and 73 in these controls responsive to particular levels of moisture being reached in the garment. Thus, relay coil 72 in the moistening control M, when energized, opens the normally closed switch 68 to terminate the moistening step; and relay 73- in the drying control, when energized, closes the normally open switch 69 to stop the drying step. Normally open switch 75 in power input line 60 to the drying control D is also closed by the relay 72 to start the drying step automatically upon the moistening control M responding to the proper moisture level.

The controls M and D are similar to one another in so far as both have the sensor probes that contact the garment and other components of like nature. The control will thus be described together with all even number references being for the moistening control M and all odd number references being for the drying control D.

The AC. voltage across lines 60 and 62 is converted to DC. voltage for each control M and D by half wave rectifiers 80, 81 each including a resistor 84, 85 in series therewith and a capacitor 88, 89 in parallel across lines 90, 91 and the common ground 62. From an alternating 120-volt potential, a DC. potential of approximately 170 volts is achieved for each control M and D; and line 91 is at a higher potential than ground line 62 for control D and line 9 is at a lower potential than ground line 62 for control M.

Sensor probes 42, 43 and 46, 47 are connected between lines 90, 91 and ground 62 in series with a fixed resistor 94, 95 and a variable resistor 98, 99. A wiper contact 100, 101 engaging resistor 98, 99 is connected through resistor 104, 105 to line 108, 109, and this line in turn is connected to the lower line potential 90, 62 by parallel connections including on the one hand capacitor 112, 113, and on the other hand neon bulb 116, 117 and resistor 118, 119. Relay 72, 73 and half wave rectifier 122, 123, in a parallel arrangement are connected in series between the higher potential line 62, 91 and line 124, and a silicon controlled rectifier 128, 129 and a resistor 132, 133, in a parallel arrangement, connect line 124, 125 and the lower potential line 90, 62. The line 138, 139 between the neon bulb 116, 117 and resistor 118, 119 is similarly connected to the gate of the silicon controlled rectifier 128, 129 and the voltage at this location controls the operation of the rectifier.

The more moisture contained in the fabric located on the press and between the probes 42, 44 and 45, 47 the lower the electrical resistance and thus the smaller vo tage drop across the probes. The voltage taken off of the resistors 98, 99 by the wipers 100, 101 is sufficient in any event to charge the capacitor 112, 113. The neon bulb 116, 117 has the characteristic of being a gap across lines 108, 109 and 138, 139 at all voltages below the ionizing potential of approximately 70 volts, but after the gas in the bulb has ionized, the circuit across the bulb is completed to permit the charged capacitor 112, 113 to discharge and activate the silicon controlled rectifier 128, 129. The silicon controlled rectifier in the static condition presents open contacts between lines 124 and 90, and 125 and 62, but upon having s-utficient gate voltage applied from line 138, 139, closes to energize the relay 72, 73.

Each control M and D operates similarly in a sense but their action will be described separately as would occur during a typical pressing cycle. Thus, upon closing the press head 22 and the limit switch 63, the moistening control M is energized. The voltage drop across the sensor probes 42, 44 at first is quite high since the dry fabric has high resistance, but the voltage drop decreases as the fabric is moistened. Depending on the adjustment of the wiper 100 on resistor 98 a certain percentage of the voltage is divided between the two separate legs including the resistor 94 on the one hand and the resistor 104 on the other hand. The neon lamp 116 eventually is subjected to sufficient voltage to ionize and complete the circuit between lines 108 and 138, and the capacitor 112 discharges through the completed circuit across the lamp to energize the silicon controlled rectifier 128. Relay 72 is thus energized to open switch 68 and terminate the moistening cycle. The relay 72 also closes switch 75 to energize the drying control D.

In the drying control D the fabric is initially moist so that the voltage drop is initially small across the sensor probes 45, 47 and less voltage is directed through wiper 101 to the line 109. However, as the fabric dries and the resistance increases, the potential at line 109 increases sufficiently to ionize the lamp 117 and discharge the charged capacitor 113 for activating the silicon controlled rectifier 129. This energizes the relay 73 which closes switch 69 and in turn terminates the drying step of the machine.

To adjust the various levels of moisture at which the controls respond, the wipers 100, 101 need only be shifted along the resistor 98, 99 which charges the relative resistances of the separate legs of the circuit to charge the potential sensed by the neon lamp. In the moistening control M, moving the wiper 100 along the resistor 98 toward line 146 means the fabric must absorb more moisture to terminate the moistening sequence; whereas in the drying control D, shifting the wiper 101 towards the line 147 means the fabric must be dried more to terminate the drying cycle.

In order to permit a midscale positioning of the wiper relative to the resistor for a given moisture level, a fine tune adjustable resistor 144, 145 is connected in para el between line 146, 147 and the wiper line 100, 101. This resistor 144, 145 can thus be set upon calibration of the machine to provide that at some given moisture level the wiper approximates the midpoint scale of the resistor and permits adjustment both for a wetter or drier contro In the control, the high impedance elements 104, 105 and 112, 113 prevent a static charge on the probes from activating the neon lamp control. The neon lamp in turn serves as a powerless voltage threshold switch, so that prior to reaching the threshold voltage substantially no current passes through the lamp but once the threshold has been reached and device becomes essentially a closed path of nominal resistance. A solid state equivalent to the neon lamp would be a four layer diode or thyristor, which is marketed by General Electric Company under the trade name of Diac.

While the cycle described initially started with the moistening sequence and automatically energizes the drying sequence, the opposite can of course occur. Similarly, it might be desirable to utilize only one of the particular controls, or to have other intermediary steps performed before operating the other control.

What is claimed is:

1. In a fabric conditioning machine, the combination of means to moisten the fabric and means to dry the fabric, and separate operating means to control the operation of the moistening and the drying means; spaced sensor probes disposed to contact the fabric and complete an electric circuit where the voltage drop across the probes varies inversely as the moisture level of the fabric; means to sense voltage drop changes in the circuit; and means responsive to the sensing means to control the operating means upon predetermined moisture levels of the fabric being reached.

2. A fabric conditioning machine combination according to claim 1, wherein the sensing means includes a normally open voltage responsive switch that is closed at the predetermined moisture levels.

3. A fabric conditioning machine combination according to claim 2, wherein the responsive means includes a silicon controlled rectifier that is fired by the sensing means upon the predetermined moisture level of the fabric being reached, operable thereby to complete a second circuit including a relay for control of the operating means.

4. A fabric conditioning machine combination according to claim 3, wherein an adjustable resistor is disposed in the circuit with the sensor probes operable upon adjustment to vary the relative voltage drop change sensed by the sensing means at any specific moisture level and thereby vary the critical predetermined moisture level.

5. In a fabric conditioning machine, the combination of a first circuit including a control rectifier and a solenoid that controls the operation of the machine; a second circuit including a first series leg having a first resistor and pair of spaced electric probes and second series leg having a second resistor and a capacitor, the second leg being connected off the first series leg between the first resistor and probes, and said probes being disposed to contact said fabric where the voltage drop across the probes increases as the fabric moisture level approaches more complete dryness; a third circuit including a voltage sensitive switch connected to the second series leg between the second resistor and capacitor and connected to the first circuit at the gate of the control rectifier, and the switch having open contacts that close upon a predetermined energizing voltage level being reached corresponding to a specific fabric moisture level operable to fire the control rectifier and complete the first circuit; and one of the second circuit resistors being adjustable for controllably operating the machine at various moisture levels of the fabric.

6. A fabric conditioning machine combination according to claim 5, wherein the voltage sensitive switch is in the form of a neon lamp.

7. A fabric conditioning machine combination according to claim 5, wherein the adjustable resistor in the second circuit is in the form of a resistor in one leg and a wiper slidably engaging the resistor and providing thereby the connection between the first and the second legs of the second circuit.

8. In a fabric conditioning machine, the combination of means to moisten the fabric and means to dry the fabric, and separate operating means to control the operation of the moistening and drying means including respective first circuits each having a control rectifier and a sole noid; second circuits each including a first series leg having a first resistor and pair of spaced electric probes and second series leg having a second resistor and a capacitor, the second leg being connected off the first series leg between the first resistor and probes, and said probes being disposed to contact said fabric where the voltage drop across the probes increases as the fabric moisture level approaches more complete dryness; and third circuits each including a voltage responsive switch connected to the second series leg between the second resistor and capacitor and to the first circuit at the gate of the control rectifier, and each switch having open contacts that close upon a predetermined energizing voltage level being reached corresponding to a specific fabric moisture level operable to fire the respective control rectifier and complete the respective first circuit.

9. A fabric conditioning machine combination according to claim 8, wherein one of the resistors of each second circuit is adjustable for controllably operating the moistening and drying means of the machine at various fabric moisture levels.

10. A fabric conditioning machine combination according to claim 8, wherein one of the first circuits further includes switch means and the other of the first circuits further includes means to actuate said switch means upon energization of said other first circuit.

11. A fabric condition machine combination according to claim 10, wherein said other first circuit further includes limit switch means which is closed automatically when the machine is properly dressed and ready to cycle.

12. In a fabric conditioning machine, the combination of means to moisten the fabric and means to dry the fabric, and separate operating means to control sequentially the operation of the moistening and drying means including respective first circuits each having switch means and a solenoid; second circuits each including a first leg having a pair of spaced electric probes and a second leg connected off the first leg, and said probes being disposed to contact said fabric where the voltage drop across the probes increases as the fabric moisture level approaches more complete dryness; third circuits each including a voltage responsive switch connected to the second circuit in the second leg and operable to close the first circuit switch means upon a predetermined fabric moisture level being reached; and one of the first circuits further including second switch means and the other of the first circuits further including means to actuate said second switch means upon energization of said other first circuit.

13. A fabric conditioning machine combination according to claim 12, wherein said voltage responsive switch is a neon lamp.

14. A fabric conditioning machine combination according to claim 12, wherein said probes engage opposite sides of the fabric.

References Cited 5 UNITED STATES PATENTS 3,256,623 6/1966 Radford 38l5 3,364,585 l/1968 Fish et a1. 34-45 10 CARROLL B. DORITY, JR., Primary Examiner US. Cl. X.R. 3815 

